1. Field of the Invention
This invention relates to a cyclone having a deblocking device.
2. Discussion of Prior Art
It is known to use cyclone separators in the offshore oil industry for separating oil and water. However, the mixtures to be separated sometimes contain solid material e.g. mud, sand or organic material, and this can block the outlets of the separator(s). Since a large number of cyclone separators are used, arranged in series or in parallel in larger vessels, it is difficult to identify and isolate the particular outlet in which the blockage has occurred.
Hydrocyclones in this type of application have conventionally been "backwashed" by admitting the inter pressure to the overflow chamber of the pressure vessel, thereby causing a reversal of the direction of flow through the overflow orifice. This has the limitation that the maximum pressure differential that can be developed over a blocked orifice is equal to the pressure drop caused by the reverse flow through the other unblocked or partially blocked orifices. A large reverse flow and prolonged "backwashing" may therefore be required to produce any beneficial effect on blocked or partially blocked orifices. Additionally the purpose of the hydrocyclones is to remove residual oil from the produced water to meet legislative requirements for discharge, and any reverse flow carries back onto the hydrocyclone quantities of the separated oil and prevents the hydrocyclone from removing any oil from the incoming flow. This is clearly undesirable because the quality of the water leaving the underflow of the cyclone may become worse than the water entering the cyclone.